Tubular fluid heater with built-in soot blower, and method effected thereby



Jan. 1, 1957 J. KOLLING TUBULAR FLUID HEATER WITH BUILT-IN soo'r BLOWER, AND METHOD EFFECTED THEREBY Filed Feb. 24, 1953 FIG.1

INVENTOR Johann K5712 BY ATTORNEY United States Patent-"O TUBULAR FLUID HEATER WITH BUILT-IN SOOT BLOWER, AND METHOD EFFECTED THEREBY Johann Kolling, Oberhausen, Germany, assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application February 24, 1953, Serial No. 338,543

2 Claims. (Cl. 122-392) This invention relates to heat exchange apparatus, and more particularly to an improvement in tubular heat exchangers whereby they may be effectively maintained in optimum operative condition.

The invention may be considered as exemplified in a convection superheater for a high temperature vapor generating unit. The superheater includes a bank of spaced tubes disposed within the heat transfer zone and connected so that there may be relative movement be tween adjacent or successive tubes. According to the invention, selected tubes, distributed throughout the bank of superheater tubes, have disposed therein soot blowing tubes with lateral outlets through jets at distributed positions along the lengths of the enclosing tubes. Soot blowing fluid at a temperature of the order of the superheated vapor within the superheater is periodically introduced in the soot blower tubes for exit through the jets, this jet action having a reaction which causes a acteristics relative to the inherent vibration characteris- I tics of the tube. This vibration is transmitted through the connections to successive and adjoiningsuperheater tubes so that the jet action of the multiplicity of soot blowing jets to remove particles from the exterior surface of the superheater tubes is augmented by the regular shaking or vibration of all of the superheater tubes. In one particular embodiment of the invention, the fluid impact of the jet action of the soot blower tubes is accompanied by an augmented mechanical impact transmitted to the successive superheater tubes through lost motion connections between adjacent tubes.

In a more specific sense, the invention as above outlined involves a pendent convection superheater for superheating high pressure vapor to temperatures of the range of 1000 to 1100 F., the superheater being subject to gas temperatures which may be as high as 2500 F. Under certain conditions of use, this superheater is protected by a screen of vapor generating tubes disposed between the foremost superheater tubes and the source of gas flow. In this arrangement, the vapor generating tubes in front of the superheater tubes also contain soot blower tubes arranged with laterally directed jets for jet action of the soot blowing fluid through the walls of the containing tubes. The soot blower tubes disposed internally of the vapor generating tubes are connected to a source of soot blowing fluid of a temperature of the order of the temperature of the saturated vapor within the vapor generating tubes. When a multiplicity of vapor generating tubes are so employed, they may be subject to the above indicated method of combining the fluid jet action and the mechanical vibration of the tubes set up by that jet action to remove particles from the exterior surfaces of the vapor generating tubes.

The invention will be described with reference to particular apparatus, and the invention will be specifically and clearly set forth in the appended claims. For a 2,775,958 Patented Jan. 1, 1957 ice clear understanding of the invention reference should be had to the following description which relates to the specific apparatus disclosed in the accompanying drawmg.

In the drawing:

Fig. 1 is a fragmentary view of a secondary or high temperature superheater receiving superheated steam from a suitable source and further superheating the steam. This superheater is shown as disposed between rows of vapor generating tubes and is subject to the flow of high temperature gases from a furnace.

Fig. 2 is a fragmentary horizontal section on the line 2--2 of Fig. 1, and

Fig. 3 is a fragmentary horizontal section illustrating a type of lost motion connection between successive superheater tubes, on the line 33 of Fig. 1.

The high temperature superheater indicated generally at 10 in Fig. 1 is intended for incorporation in a steam generating unit involving a high temperature furnace from which the gases flow to the superheater in the direction of the arrow 11. The superheater has an inlet header 12 which receives steam through tubes 13, from a primary or low temperature superheater such as the superheater 76, 78 of the U. S. patent to Woolley 2,553,493, May 15, 1951. Alongside the inlet header 12 is the superheater outlet header 14, platens of return bend superheater tubes being pendently supported from these headers. Some of the spaced platens may be formed by the tubes 15 leading from the inlet header 12. Each of these platens is shown as having lower and upper return bends 1619 with the last of these return bends having its connection to the outlet header 14 formed by the tubular section 20.

Of the remaining superheater platens, alternating, or selected platens have their inlet tubular sections 21 of a diameter larger than the tube 15, as clearly indicated in the upper part of Fig. 1. Each tubular section 21 extends down to the return bend 22 where the conduit continuesthrough the successive tubular sections and return bends 2325 to outlet tubular sections similar to the tubular sections 20, connected to the outlet header 14.

The larger diameter tubular section 21 has disposed therein a smaller tube 26 connected to a source of soot blowing fluid of a temperature of the order of the superheated vapor flowing from the header 12. This soot blowing fluid is also under such pressure that it may develop effective jet action through laterally directed jets such as 27. These jets communicate with the interior of the soot blower tube 26 and extend through the wall of the large diameter superheater tube 21 at various and distributed positions throughout the height of the latter, and with the jets directed at different radial angles toward the remaining tubular sections of the superheater.

'The separate superheater platens leading from the tubes 15 and 21 may combine to form unitary platens when the lower end of each tube section 15 has at its lower end a return bend such as indicated at 16 in Fig. 2. This return bend extends below the return bend 22 and also around the next successive upright tubular section 31 leading from the return bend 22 which is connected to thelarge diameter superheater tube 21. A similar return bend 18 is provided at the lower endof the next succeeding downflow leg of the return bend 17.

The succeeding tubes such as 31, 32 and 33 in Fig. 3 are connected by lost motion connections particularly shown in Fig. 3, these lost motion connections being disposed in a horizontal zone indicated at 34 in Fig. 1. Fig. 3 shows the tube 31 as having the L-shaped metallic extensions 35 and 36 welded thereto at 37 and 38 to form the T-slot for receiving the T connection 37' which is welded to the next successive tube 32 at 39. A similar T extension '40 is secured to each of thetubes 33, and is received in a T slot formed by the similarly L-shaped extensions 41 and 42 similarly welded to the tube 32.

The jet structures at positions such as -2 7 inFig. 1 due to their lateral direction have, under the influence of high velocity and high pressure soot blowing fluid, a reaction effect upon the tube 21 to cause-it to moveto the left in Fig. 1 and thereby bring the L-shaped elements of the lost motion connection between thetube 21 and the succeeding tubes into impact with the interengaged T-heads. This impact is transmitted from tube to tube, setting up displacement ofthe tubes. When the superheater is pendently supported, as by the inlet and outlet tubular sections and 20, the tendency isfor the successive superheater tubes to spring reversely upon each termination of the connection of the soot blowing tubes with the source of fluid. Each entry of soot blowing fluid is of short duration, and, in practice, there would be a predetermined periodicity of the successive entries of soot blowing fluid, this periodicity being related to the inherent vibration characteristics of the superheater components so as to set up impact introduced vibrations in the superheater tubes. These vibrations combine with the jet action of the soot blowing fluid to loosenand remove from the superheater tubes any particles which may have been secured thereto.

The superheater of Fig. 1 is shown as disposed between a front row of vapor generating tubes 45-and a rear row of vapor generating tubes '46. These tubes are preferably extensions of furnace wall vapor generating tubes. The rows of tubes 45 and 46 are disposed in furnace wall alignment beneath the superheater as indicated at 47. To the left of the superheater and at a higher level, the front and rear rows of tubes 45 and 46 are disposed in roof forming alignment as indicated at 47. At this position and to the left of this position, these tubes may continue so as to constitute-a part of the roof of a high temperature furnace. They preferably continue to a vapor and liquid drum or to a position at which the generated vapor is separated from-the mixtures of vapor and liquid which move upwardly through the vapor generating tubes.

The vapor generating tubes 45 and 46 may have internally disposed therein smaller diameter soot blower tubes such as 48. In Fig. 1, tube 48 is indicated as having at its lower end a laterally directed soot blower jet 49 directed toward the superheater tubes 21. The soot blower tubes 48 may extend throughout a greater portion of the vapor generating tubes 45- and may have a plurality of soot blower jets similar to-the jet 49 distributed throughout the lengths of the tubes 45. These soot blower tubes 48 are connected-to-asource of soot blowing fluid under pressure and have a temperatureof the order of the temperature of the-saturated'fluid within the tubes 45. The vertical portions of the tubes 46 alongside the superheater have internal soot blower tubes and arrangements of soot blower jets similar tothose' of the tubes 45, but with the jets directed toward the' adjacent superheater tubes.

The soot blowing vapor'generating tubes' and superheater tubes may be considered as of a permanent soot blower type, and in each case the internally disposed soot blower tubes are protected'against the high gas temperatures by reason of the fact that 3 the soot blower tubes are surrounded by a fluid of much lower temperature than the temperature of the gases. In each casealso, stressing of the soot blower jets due to thermal gradients is minimized by reason of the fact that the soot blowing fluid passing through the jets is of a temperature similar to or of the order of the temperature of the fluid surrounding the soot blower tubes.

The general type of vapor generator to which this in- "vention' relatesis sho'wn'in the above identifiedWoolley patent, with applicants superheater arranged as a secondary or high temperature superheater, relative to the furnace and the primary superheater, in a manner similar to the patentees superheater including the platens constituting the banks of tubes 60 and 62.

'Wh'ilethe invention has been described with reference to the particular apparatus shown in the accompanying drawing it is to be appreciated that the invention is not limited to all of the details thereof, and that themethod of the invention is not limited to the successive acts referred to in the description of the operation of the apparatus. -The invention is rather to be considered of a scope commensurate with the scope of the subjoined claims.

What is claimed is:

1. In convection fluid heat exchange apparatus including a pendent bank of horizontally spaced upright tubes normally externally subject to high temperature gas flow, means connecting the tubes for series flow therethrough of a fluid to be heated, soot blowing tubes of smaller diameter disposed within some of the first mentioned'tubes, laterally directed soot blower jet structures communicating with the soot blower tubes and extending through the walls of the pertinent soot blower enclosing tubes toward the remaining tubes of the bank of tubes, means for connecting the soot blower tubes to a source of pressurized soot blowing fluid of a temperature of the order of the temperature of the fluid to be heated, said last named connecting means being adapted to transmit soot blowing fluid to the jet structures in successive jet actions of a periodicity promoting vibration of the tubes, and impact transmitting lost motion connections between successive and adjacent tubes of said bank of tubes, the periodicity of the successive jet actions and the impact transmitting connections serving to set up vibrations of the tubes of said bank of tubes.

2. Inconvection fluid heat exchange apparatus including a pendent bank'of horizontally spaced upright tubes normally externally subject to high temperature gas flow,'m-eans connecting the tubes for series flow therethrough of a fluid'to'be treated, soot blowing tubes of smaller diameter disposed within some of'the first mentioned tubes, laterally directed soot blower'jet structures communicating with the soot blower tubes and extending through the walls of the pertinent soot blower enclosing tubes toward the remaining tubes of the bank of tubes, means for connecting the soot blower tubes to a source of pressurized soot blowing fluid, said last named connecting means being adapted to transmit soot blowing fluid to the jet structures in successive jet actions of a periodicity promoting vibration of the tubes, and impact transmitting connections between successive and adjacent tubes of said bank of tubes, the periodicity of the successive jet actions and the impact transmitting connections serving to set up vibrations of the tubes of said bank of tubes.

References Cited in the file of this patent UNITED STATES PATENTS 1,416,552 Garland May 16, 1922 1,829,119 Thery c 'Oct. 27, 1931 1,930,782 Turner -Oct. 17, 1933 1,966,912 Turner July 17, 1934 2,023,108 Thomas et al Dec. 3, 1935 2,027,495 Turner Jan. 14, 1936 2,060,910 Turner Nov. 17, 1936 2,110,533 Snow Mar. 8, 1938 2,183,496 "Peters Dec. 12, 1939 2,350,202 Thomas May 30,1944 2,351,163 Thomas June 13, 1944 

